Sinonasal schwannoma masquerading as an IgG4- related nasal mass.

An elderly (8th decade) diabetic patient presented with insidious, painless protrusion of the right eye for 1 month, associated with nasal congestion. Past history included healed serous chorioretinopathy in the right eye (>30 years back) and recently diagnosed (1 year prior) autoimmune IgG4-related pancreatitis for which he was on long-term corticosteroids. On nasal endoscopic examination, a well circumscribed mass was found in the right nasal cavity. Keeping in mind the systemic diagnosis, the sinonasal mass was suspected to be a IgG4-related disease. An endoscopic biopsy was performed and revealed a surprise diagnosis of grade 1 nasal schwannoma. [ABSTRACT FROM AUTHOR]